Method of constructing an inflatable support system having thermoplastic polyurethane constuction

ABSTRACT

A method for constructing an inflatable support system by forming a first layer comprised of thermoplastic polyurethane and a second layer comprised of thermoplastic polyurethane. At least one coil is formed from thermoplastic polyurethane and a first end of the coil is attached to the first layer. A second end of the coil is attached to the second layer.

RELATED APPLICATIONS

The present application is a division of and claims benefit under 35 U.S.C. §121 of Nonprovisional application Ser. No. 11/202,769, filed Aug. 12, 2005.

BACKGROUND

1. Field of the Invention

The present invention relates to the field of inflatable support systems, particularly to a method of constructing an inflatable support system at least in part from thermoplastic polyurethane material.

2. Related Art

Inflatable mattresses have been available for many years, and they are commonly used as both temporary and permanent sleeping arrangements. In addition, inflatable mattresses are often used outdoors on camping trips or other overnight trips. Because these mattresses are so often used while traveling, it is desirable to make them as light and portable as possible to minimize packing space and maximize convenience, while at the same time retaining the strength to resist punctures and leakage from the seams under normal use.

Furthermore, new inflatable mattresses that more closely resemble conventional mattresses are often very large, sometimes even having multiple chambers. A king-size conventional inflatable mattress that inflates to a height of almost three feet can weigh nearly 125 pounds when deflated. This weight may severely limit its portability.

These shortcomings are addressed by constructing a mattress from thermoplastic polyurethane (“TPU”), a recyclable material that is lighter than polyvinyl chloride (“PVC”) or rubber, materials that have been conventionally used to construct inflatable mattresses. In the past, it has been prohibitively expensive to work with TPU, and as it is very thin, it has been difficult to weld to form the material into inflatable objects that require a rigid structure.

In the past, TPU material has been used in self-inflating mattress pads, but such pads incorporated a foam internal structure that was glued to the TPU sheets. The foam structure, while adding support to the pads, added a significant amount of weight. Such pads were much smaller than conventional inflatable mattresses, usually having a height of no more than two inches. Such a pad in the size of a conventional inflatable mattress would weigh ten pounds or more.

BRIEF SUMMARY

Disclosed herein is a method for constructing an inflatable support system by forming a first layer comprised of thermoplastic polyurethane and a second layer comprised of thermoplastic polyurethane. At least one coil is formed from thermoplastic polyurethane and a first end of the coil is attached to the first layer. A second end of the coil is attached to the second layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an inflatable mattress produced utilizing the present method;

FIG. 2 is an external view of a flange produced utilizing the present method;

FIG. 3 is an internal view of the flange of FIG. 2;

FIG. 4 is an external view of the flange of FIG. 2 with a valve attached;

FIG. 5 is a cross-sectional view of the mattress of FIG. 1 showing the internal coils;

FIG. 6 is an enlarged view of the coils of FIG. 5; and

FIG. 7 is a cross-sectional view of a coil of FIG. 5 showing the fabric layer and the TPU layer.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS

Referring in combination to FIGS. 1-6, an inflatable support system in the form of an inflatable mattress produced utilizing the present method is shown. Thermoplastic polyurethane (“TPU”) 10, is utilized to create a lighter inflatable mattress that still retains the strength of a heavier, conventional polyvinyl chloride (“PVC”) mattress. At the same time, a mattress constructed from TPU will not leach harmful chemicals such as chloride and dioxin into the environment upon disposal.

While any shape or size mattress or inflatable object can be formed using TPU, the embodiment shown is a double-size inflatable mattress. Other sizes are envisioned, as well as thicker mattresses that incorporate more than one inflatable chamber, such as the raised mattress shown in U.S. Pat. No. 6,704,559.

The present method includes a series of steps to form an inflatable mattress. First 14 and second 16 layers of TPU 10 are cut from a TPU sheet. If desired, a side gusset 18 is also cut from a TPU sheet. If desired, a layer of fabric 32 is laminated to one side of the TPU sheets 14, 16. TPU coil structures 24 are then formed from TPU material 10, and these coil structures 24 are welded via sonic or heat welding to the sides 22 of the top 14 and bottom 16 TPU sheets opposite the fabric covered sides. The side gusset 18 is then welded to the outside edges 20 of the top 14 and bottom 16 sheets in a manner such that TPU is welded to TPU.

An additional step of forming a flange 24 from TPU may also be included in the present method. A flange mold is supplied and TPU pellets are heated until a liquid is formed. This liquid is poured or injected into the flange mold and the mold may be heated to set the material. Alternatively, the TPU may simply be allowed to cool in the mold until it sets. The fully-formed TPU flange 26 is then removed from the mold. An opening is formed in the side gusset 18, top sheet 14 or bottom sheet 16 to accept the flange 26. The flange 26 is then welded via sonic or heat welding in the opening of the side gusset 18 of the inflatable mattress, or to the opening in the top 14 or bottom 16 layer of the inflatable mattress 12 if a side gusset 18 is not provided. The flange 26 is welded to the internal wall 30 of the side gusset 18 or the internal wall 22 of the top 14 or bottom 16 sheet of TPU such that TPU is welded to TPU, creating a substantially airtight weld. A valve 28 such as the valve 28 shown in FIG. 4 can then be attached to the flange 26.

In the illustrated embodiment, a mattress produced utilizing the present method has at least one inflatable substantially airtight chamber 12. This inflatable chamber 12 has a top 14 and a bottom 16 layer, each layer 14, 16 being formed from a thin sheet of TPU material 10. The TPU material 10 preferably has a thickness of no more than 0.2 mm, and is cut to form the desired mattress size. Greater thicknesses of TPU could also be used if increased strength is needed, but this would also increase the weight of the mattress 12. Another piece of TPU material is cut to form a side gusset 18 for the mattress 12. The side gusset 18 is welded via sonic or heat welding to the outside edges 20 of the top 14 and the bottom 16 layers. Alternatively, the top 14 and bottom 16 layers can be welded to each other at their outer edges 20, thereby eliminating the need for a separate side gusset 18.

In order to prevent the inflatable mattress 12 from ballooning out on its top and bottom sides, support structures in the form of internal coils, shown in FIGS. 5-7, are provided. To create the internal coil construction, TPU is cut into belts, which are then welded via sonic or heat welding to the internal sides 22 of the top 14 and bottom 16 sheets of TPU 10. The coils 24 in the illustrated embodiment are welded in a four-sided shape having slightly concave sides, but they could be welded to the top 14 and bottom 16 layers using a more conventional oval shape, or any other shape desired. The coils 24 are preferably aligned in parallel rows and have an elongated oval shape in cross-section. The overall effect of the coil shape and arrangement is to form a box-like construction, similar to a conventional mattress. This also adds support and strength to the inflatable mattress 12.

Referring to FIGS. 1-4, a mattress formed utilizing the present method includes a flange 26 constructed from TPU material designed to have a valve 28 attached to it for inflation and/or deflation of the inflatable mattress 12. On conventional inflatable mattresses, such a flange would be formed from heavy PVC, thus adding more weight to the mattress. In the present method, the flange 26 is preferably formed by melting TPU material, which can be in the form of TPU pellets, into a liquid form. This liquid is then poured into a flange-shaped mold to fill the entire mold cavity. The mold is then heated until the TPU material is set. At this point, the mold is opened and the TPU material is allowed to cool. An opening is defined in the side gusset 18, and the finished flange 26 is attached via heat or sonic welding to the internal wall 30 of the side gusset 18. The weld forms a substantially airtight seal around the flange 26. Alternatively, if a side gusset 18 is not used, the flange 26 can be welded to the internal wall 22 of the top 14 or bottom 16 layer of TPU.

The present method may be adjusted such that the finished flange 26 can accept a valve 28 that allows both inflation and deflation of the inflatable mattress 12 such as that shown in U.S. Pat. Nos. 5,627,363; 5,367,726; and 6,237,621. Alternatively, other types of valves could be formed using the present method as well as different flange shapes adapted to the specific valves. Furthermore, the present method can be used to form a second flange from TPU. This second flange (not shown) can be defined on the side gusset 18 for receiving a pump.

In another embodiment of the present method, a fabric layer 32 is utilized to provide even more strength without significantly increasing the weight of the inflatable mattress 12. As in the previous embodiment, a top layer 14, bottom layer 16, and a side gusset 18, if desired, are formed from TPU 10. A thin layer of fabric or flocking is then laminated or applied to one side of the TPU sheets using polyurethane glue. The opposite side 34 of the TPU sheets is left bare, in order to allow welding of the TPU coils 24 to the internal sides 22 of the top 14 and bottom 16 layers. In a preferred embodiment, the fabric is 150 Denier polyester, but other types of thin fabric layers could also be utilized. This allows the design of different colored beds, beds having soft coverings or beds having a silk screened design on them. If no fabric is used, the beds can even have a clear construction. An example of a TPU layer laminated to a fabric layer 32 and incorporating a TPU coil 24 support structure is most clearly shown in FIGS. 2-4 and 7. The fabric layer 32 is shaded for clarity in these figures. In FIG. 2, the internal wall 30 of the side gusset 18 is shown.

As a comparative example of the decreased weight of an inflatable mattress formed utilizing the present method, a double bed formed from TPU including a fabric layer and a TPU flange weighs only about eight pounds, nearly ⅓ less than a conventional PVC inflatable double bed. A bed constructed utilizing the present method is also able to withstand a 650 pound dead weight test and a life roller test consisting of an octagon roller weighing 180 pounds rolled side to side over the mattress 12 30,000 times.

It should be noted that a wide range of changes could be made to the present method without departing from its scope. As noted, the welding pattern could take different forms. The entire inflatable support system could also be constructed in any number of shapes and sizes. Additionally, the flange could take any number of shapes, dependent on the type of valve that it is designed for. The coils could also be replaced by other structural supports formed from TPU, such as TPU strips that are attached to the top and bottom layers to prevent the top and bottom layers from ballooning out upon inflation. The order of the steps of the present method could also be adjusted if necessary.

The TPU material used to form the top and bottom layers of the mattress and the flange can be any type of TPU known to one of skill in the art. The TPU can also be mixed with other materials, such as conventional PVC or rubber, before being formed into sheets. The TPU used to mold the flange can also contain other materials. Additional layers of material other than fabric could also be incorporated, such as PVC layers which could be laminated or otherwise attached to the TPU layers. If desired, an inflatable mattress could be formed from conventional PVC material and incorporate a TPU flange.

It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention. 

1. A method for constructing an inflatable support system, said method comprising the steps of: forming a first layer comprised of thermoplastic polyurethane; forming a second layer comprised of thermoplastic polyurethane; forming at least one coil comprised of thermoplastic polyurethane; attaching a first end of said coil to said first layer; and attaching a second end of said coil to said second layer.
 2. The method of claim 1, further comprising the step of forming a side gusset comprised of thermoplastic polyurethane and attaching said side gusset to said first layer and said second layer.
 3. The method of claim 2, further comprising the steps of supplying a flange mold; heating thermoplastic polyurethane pellets until they are in a liquid state; injecting said liquid into said flange mold to form a flange; removing said flange from said mold; and welding said flange to said side gusset.
 4. The method of claim 2, further comprising the step of laminating a fabric layer to at least one side of at least one of said first and said second layers.
 5. The method of claim 2, further comprising the step of applying a layer of flocking to at least one side of at least one of said first and said second layers.
 6. A method of constructing an inflatable support system, said method comprising the steps of: laminating a fabric layer to a layer of thermoplastic polyurethane to form a sheet; cutting said sheet to form at least a top and a bottom layer; cutting said sheet to form a side gusset; forming at least one coil from a sheet of thermoplastic polyurethane; welding a first end of said coil to said top layer on a side opposite said fabric layer; welding a second end of said coil to said bottom layer on a side opposite said fabric layer; and welding one edge of said side gusset to said top sheet and welding the opposite edge of said side gusset to said bottom sheet to form an inflatable chamber.
 7. The method of claim 6, further comprising the steps of: supplying a mold for a flange; melting thermoplastic polyurethane material to form a liquid; injecting said liquid into said mold; heating said mold until said thermoplastic polyurethane is permanently set; opening said mold and cooling said flange; defining an opening in said side gusset; and welding said flange to said side gusset at said opening.
 8. The method of claim 7, further comprising the step of attaching a valve to said flange.
 9. The method of claim 6, wherein said sheets of thermoplastic polyurethane are not thicker than 0.2 mm.
 10. The method of claim 7, wherein said welding steps are performed by sonic welding.
 11. The method of claim 7, wherein said welding steps are performed by heat welding.
 12. The method of claim 6, wherein said fabric is polyester.
 13. A method of manufacturing an inflatable support system, said method comprising the steps of: forming a top and a bottom layer from a flexible, substantially airtight material; forming a side gusset from a flexible, substantially airtight material; welding one edge of said side gusset to said top layer and welding the opposite edge of said side gusset to said bottom layer; supplying a mold for a flange; melting thermoplastic polyurethane material to form a liquid; injecting said liquid into said mold; heating said mold until said thermoplastic polyurethane is set; opening said mold and cooling said flange; defining an opening in said side gusset; and welding said flange to said side gusset at said opening. 